Fan Wei, Li Jiaqi, Wei Lihong, Xu Yan
State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China.
State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China.
Carbohydr Polym. 2022 Aug 1;289:119442. doi: 10.1016/j.carbpol.2022.119442. Epub 2022 Apr 2.
Carboxylated cellulose nanocrystals prepared by TEMPO-mediated oxidation exhibit a distinct ability to form nematic order, however, their ability to form chiral nematic films remains relatively unexplored. In this study, bleached cotton pulp hydrolyzed with hydrochloric acid and oxidized by TEMPO-mediated oxidation produce carboxylated cellulose nanocrystals with different aspect ratios 33.1, 32.8, 30.9, 29.0 and 28.9, and surface charge densities 0.16, 0.56, 1.00, 1.25, and 1.42 e·nm. By tuning the aspect ratio and surface charge density, the optimal carboxylated cellulose nanocrystals producing left-handed chiral nematic films by evaporation-induced self-assembly are obtained. The left-handed chiral nematic films enable selective reflection of left-handed circularly polarized light with the peak wavelength tunable from the visible to the near-infrared regime by modifying the characteristics of nanorods and suspensions. Such carboxylated cellulose nanocrystal films transform spontaneous luminescence to right-handed circularly polarized luminescence with the peak luminescence dissymmetry factor of -0.51.
通过TEMPO介导氧化制备的羧化纤维素纳米晶体表现出形成向列相序的独特能力，然而，它们形成手性向列相薄膜的能力仍相对未被探索。在本研究中，用盐酸水解并经TEMPO介导氧化的漂白棉浆产生了长径比分别为33.1、32.8、30.9、29.0和28.9，表面电荷密度分别为0.16、0.56、1.00、1.25和1.42 e·nm的羧化纤维素纳米晶体。通过调节长径比和表面电荷密度，获得了通过蒸发诱导自组装产生左旋手性向列相薄膜的最佳羧化纤维素纳米晶体。左旋手性向列相薄膜能够选择性反射左旋圆偏振光，通过改变纳米棒和悬浮液的特性，其峰值波长可在可见光到近红外范围内调节。这种羧化纤维素纳米晶体薄膜将自发发光转变为右旋圆偏振发光，峰值发光不对称因子为-0.51。
